<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="bootstrap-3.3.7-dist/css/bootstrap.css">
    <style>
        div{
            width: 100px;
            height: 100px;
            background-color: red;
        }

    </style>
</head>
<body>

<div class="pull-right">
    <button type="button" class="close" aria-label="Close"><span aria-hidden="true">&times;</span></button>
</div>
<div class="center-block">
    <button type="button" class="close" aria-label="Close"><span aria-hidden="true">&times;</span></button>
</div>
</body>
</html>